The Caenorhabditis Genetics Center (CGC) is the sole comprehensive repository and distribution center for the nematode Caenorhabditis elegans, a premier model organism for biomedical research studies. The overall objective of this animal resource is to promote research on C. elegans by acquiring, maintaining, and distributing genetically characterized nematode stocks. Researchers throughout the world use genetic stocks obtained from the CGC in diverse basic and applied research endeavors, as well as for hand-on teaching of experimental science. Studies using this premier model organism have led to fundamental insights into basic biological mechanisms, including the genetic basis of programmed cell death, the discovery of microRNAs, and the mechanism of RNA interference in animals. The nematode has also proved important for understanding mechanisms of cancer progression and other diseases including Alzheimer's and Parkinson's, as well as for revealing basic mechanisms underlying human development. In addition, C. elegans serves as a key model for illuminating our understanding of parasitic nematodes with relevance to human and livestock health. As the only general stock center for C. elegans, the CGC is an extremely important international research resource, supporting research in these diverse areas and educational endeavors. The CGC provides more than 30,000 strains are distributed per year to thousands of laboratories; with a collection of over 19,000 unique strains, still expanding in proportion to the growth of the field, the CGC not only facilitates research, but also ensures that valuable strains are preserved. The CGC distributes strains upon request through an on-line ordering system. A scheme of user fees helps to defray costs and support CGC activities. The CGC also includes a research component aimed at enhancing the CGC collection. Our close monitoring of user needs, ties with the C. elegans community, and focus on genetic tools has given us a unique perspective in devising a research component. Two aims will be pursued, one focused on expanding the genetic tool-kit by generating intrachromosomal inversions for use as crossover suppressors. The other aim is to complete the collection of null mutations in microRNA genes.